Sugar signaling modulates SHOOT MERISTEMLESS expression and meristem function in .

In plants, development of all above-ground tissues relies on the shoot apical meristem (SAM) which balances cell proliferation and differentiation to allow life-long growth. To maximize fitness and survival, meristem activity is adjusted to the prevailing conditions through a poorly understood integration of developmental signals with environmental and nutritional information. Here, we show that sugar signals influence SAM function by altering the protein levels of SHOOT MERISTEMLESS (STM), a key regulator of meristem maintenance.

Strigolactone signalling inhibits trehalose 6-phosphate signalling independently of BRC1 to suppress shoot branching.

The phytohormone strigolactone (SL) inhibits shoot branching, whereas the signalling metabolite trehalose 6-phosphate (Tre6P) promotes branching. How Tre6P and SL signalling may interact and which molecular mechanisms might be involved remains largely unknown. Transcript profiling of Arabidopsis SL mutants revealed a cluster of differentially expressed genes highly enriched in the Tre6P pathway compared with wild-type (WT) plants or brc1 mutants.

Direct and indirect responses of the Arabidopsis transcriptome to an induced increase in trehalose 6-phosphate.

Trehalose 6-phosphate (Tre6P) is an essential signal metabolite that regulates the level of sucrose, linking growth and development to the metabolic status. We hypothesized that Tre6P plays a role in mediating the regulation of gene expression by sucrose. To test this, we performed transcriptomic profiling on Arabidopsis (Arabidopsis thaliana) plants that expressed a bacterial TREHALOSE 6-PHOSPHATE SYNTHASE (TPS) under the control of an ethanol-inducible promoter.

S basic leucine zipper transcription factors shape plant architecture by controlling C/N partitioning to apical and lateral organs.

Plants tightly control growth of their lateral organs, which led to the concept of apical dominance. However, outgrowth of the dormant lateral primordia is sensitive to the plant's nutritional status, resulting in an immense plasticity in plant architecture. While the impact of hormonal regulation on apical dominance is well characterized, the prime importance of sugar signaling to unleash lateral organ formation has just recently emerged.

The trehalose 6-phosphate phosphatase family in plants.

Trehalose 6-phosphate (Tre6P), the intermediate of trehalose biosynthesis, is an essential signalling metabolite linking plant growth and development to carbon metabolism. While recent work has focused predominantly on the enzymes that produce Tre6P, little is known about the proteins that catalyse its degradation, the trehalose 6-phosphate phosphatases (TPPs). Often occurring in large protein families, TPPs exhibit cell-, tissue- and developmental stage-specific expression patterns, suggesting important regulatory functions in controlling local levels of Tre6P and trehalose as well as Tre6P signalling.

Singlet oxygen-induced signalling depends on the metabolic status of the Chlamydomonas reinhardtii cell.

Using a mutant screen, we identified trehalose 6-phosphate phosphatase 1 (TSPP1) as a functional enzyme dephosphorylating trehalose 6-phosphate (Tre6P) to trehalose in Chlamydomonas reinhardtii. The tspp1 knock-out results in reprogramming of the cell metabolism via altered transcriptome. As a secondary effect, tspp1 also shows impairment in O-induced chloroplast retrograde signalling.

Multi-year field trials provide a massive repository of trait data on a highly diverse population of tomato and uncover novel determinants of tomato productivity.

Tomato (Solanum lycopersicum) is a prominent fruit with rich genetic resources for crop improvement. By using a phenotype-guided screen of over 7900 tomato accessions from around the world, we identified new associations for complex traits such as fruit weight and total soluble solids (Brix). Here, we present the phenotypic data from several years of trials.

Next generation editors.

The Journal of Experimental Botany is pleased to announce the appointment of six early career researchers as editorial interns: Francesca Bellinazzo (Wageningen University and Research, the Netherlands), Konan Ishida (University of Cambridge, UK), Nishat Shayala Islam (Western University, Ontario, Canada), Chao Su (University of Freiburg, Germany), Catherine Walsh (Lancaster University, UK), and Arpita Yadav (University of Massachusetts Amherst, MA, USA) (Fig. 1). The aim of this programme is to help train the next generation of editors.

In vivo protein kinase activity of SnRK1 fluctuates in Arabidopsis rosettes during light-dark cycles.

Sucrose-nonfermenting 1 (SNF1)-related kinase 1 (SnRK1) is a central hub in carbon and energy signaling in plants, and is orthologous with SNF1 in yeast and the AMP-activated protein kinase (AMPK) in animals. Previous studies of SnRK1 relied on in vitro activity assays or monitoring of putative marker gene expression. Neither approach gives unambiguous information about in vivo SnRK1 activity.

Rising rates of starch degradation during daytime and trehalose 6-phosphate optimize carbon availability.

Many plants, including Arabidopsis (Arabidopsis thaliana), accumulate starch in the light and remobilize it to support maintenance and growth at night. Starch synthesis and degradation are usually viewed as temporally separate processes. Recently, we reported that starch is also degraded in the light.

Sucrose synthases are not involved in starch synthesis in Arabidopsis leaves.

Many plants accumulate transitory starch reserves in their leaves during the day to buffer their carbohydrate supply against fluctuating light conditions, and to provide carbon and energy for survival at night. It is universally accepted that transitory starch is synthesized from ADP-glucose (ADPG) in the chloroplasts. However, the consensus that ADPG is made in the chloroplasts by ADPG pyrophosphorylase has been challenged by a controversial proposal that ADPG is made primarily in the cytosol, probably by sucrose synthase (SUS), and then imported into the chloroplasts.

Recruitment of an ancient branching program to suppress carpel development in maize flowers.

Carpels in maize undergo programmed cell death in half of the flowers initiated in ears and in all flowers in tassels. The HD-ZIP I transcription factor gene () is one of only a few genes known to regulate this process. To identify additional regulators of carpel suppression, we performed a enhancer screen and found a genetic interaction between and ().

Metabolic profiles in C3, C3-C4 intermediate, C4-like, and C4 species in the genus Flaveria.

C4 photosynthesis concentrates CO2 around Rubisco in the bundle sheath, favouring carboxylation over oxygenation and decreasing photorespiration. This complex trait evolved independently in >60 angiosperm lineages. Its evolution can be investigated in genera such as Flaveria (Asteraceae) that contain species representing intermediate stages between C3 and C4 photosynthesis.

Genetic manipulation of trehalose-6-phosphate synthase results in changes in the soluble sugar profile in transgenic sugarcane stems.

Trehalose is a non-reducing disaccharide widely distributed in nature. The trehalose biosynthetic intermediate, trehalose 6-phosphate (Tre6P) is an essential regulatory and signaling molecule involved in both regulation of carbon metabolism and photosynthesis. To investigate the effect of altered trehalose synthesis on sucrose accumulation in sugarcane (.

Impact of the SnRK1 protein kinase on sucrose homeostasis and the transcriptome during the diel cycle.

SNF1-related Kinase 1 (SnRK1) is an evolutionarily conserved protein kinase with key functions in energy management during stress responses in plants. To address a potential role of SnRK1 under favorable conditions, we performed a metabolomic and transcriptomic characterization of rosettes of 20-d-old Arabidopsis (Arabidopsis thaliana) plants of SnRK1 gain- and loss-of-function mutants during the regular diel cycle. Our results show that SnRK1 manipulation alters the sucrose and trehalose 6-phosphate (Tre6P) relationship, influencing how the sucrose content is translated into Tre6P accumulation and modulating the flux of carbon to the tricarboxylic acid cycle downstream of Tre6P signaling.

Perturbations in plant energy homeostasis prime lateral root initiation via SnRK1-bZIP63-ARF19 signaling.

Plants adjust their energy metabolism to continuous environmental fluctuations, resulting in a tremendous plasticity in their architecture. The regulatory circuits involved, however, remain largely unresolved. In , moderate perturbations in photosynthetic activity, administered by short-term low light exposure or unexpected darkness, lead to increased lateral root (LR) initiation.

Nucleotide-sugar metabolism in plants: the legacy of Luis F. Leloir.

This review commemorates the 50th anniversary of the Nobel Prize in Chemistry awarded to Luis F. Leloir 'for his discovery of sugar-nucleotides and their role in the biosynthesis of carbohydrates'. He and his co-workers discovered that activated forms of simple sugars, such as UDP-glucose and UDP-galactose, are essential intermediates in the interconversion of sugars.

Expression of a Bacterial Trehalose-6-phosphate Synthase otsA Increases Oil Accumulation in Plant Seeds and Vegetative Tissues.

We previously demonstrated that exogenous trehalose 6-phosphate (T6P) treatment stabilized WRINKLED1 (WRI1), a master transcriptional regulator of fatty acid (FA) synthesis and increased total FA content in () embryo suspension cell culture. Here, we explore lines heterologously expressing the T6P synthase (otsA) or T6P phosphatase (otsB) to refine our understanding regarding the role of T6P in regulating fatty acid synthesis both in seeds and vegetative tissues. 35S: transgenic seeds showed an increase of 13% in fatty acid content compared to those of wild type (WT), while seeds of 35: transgenic seeds showed a reduction of 12% in fatty acid content compared to WT.

The Role of Trehalose 6-Phosphate (Tre6P) in Plant Metabolism and Development.

Trehalose 6-phosphate (Tre6P) has a dual function as a signal and homeostatic regulator of sucrose levels in plants. In source leaves, Tre6P regulates the production of sucrose to balance supply with demand for sucrose from growing sink organs. As a signal of sucrose availability, Tre6P influences developmental decisions that will affect future demand for sucrose, such as flowering, embryogenesis, and shoot branching, and links the growth of sink organs to sucrose supply.